Aeration diffusers particularly as they are used in the treatment of sewage by aerobic digestion require periodic removal for maintenance.
The construction of the usual aeration tanks includes air supply mains and walk-ways along the top sides of the walls between tanks. Horizontal headers along a wall of each tank carry the submerged diffusers and are connected by vertical hanger pipes to the air supply mains. Rotary joints in the hanger pipes and a suitable hoist allow the headers to be lifted from the tank to a convenient working position above the walkway for inspection maintenance or replacement of the diffusers.
Heretofore, each rotary jointed hanger pipe assembly has been of steel construction such that its weight suitably keeps it steady in its lower, operating position in the tank. However, lifting such weight requires a sturdy hoist which is difficult to maneuver or man-handle along the walkway. In particular however, the use of plastics and resins instead of metals now offers great advantages as to cost and weight, excepting that the light weight of such equipment also now requires provisions for holding the header in the tank in its operating position.